Circuit interrupter with an improved contact structure



May 16, E95? j N GRQVES ETAL 3,32U,38@

CIRCUIT INTERRUI'TER WITH AN H HROVIZE) CONTACT IKTEUCTURII 2 Sheets-5heet 1.

Original Filed Nov. 15, I361 May 16, 1967 J, N GROVES ET AL. 335M388 CIRCUIT INTERRUPTER WITH AN IMPROVE?) CONTACT STRUCTURE 2 Sheets-Sheet .2

Original Filed Nov. 15, 1961 United States Patent 3,320,380 CIRCUIT INTERRUPTER WITH AN IMPROVED CONTACT STRUCTURE John N. Groves and Howard E. Reichcrt, Beaver, Pa., assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Original application Nov. 15, 1961, Ser. No. 152,395. D1-

vided and this application June 24, 1965, Ser. No.

6 Claims. (Cl. 200-76) This application is a division of our application Ser. No. 152,395, filed Nov. 15, 1961 now Patent No. 3,211,861, issued Oct. 12,. 1965.

This invention relates to circuit interrupters, and more particularly to manually and automatically operable circuit breakers for controlling motor, lighting and other small and moderate power electric circuits.

An object of this invention is to provide a circuit interrupter having an improved contact structure. A general object of this invention is to provide an improved circuit interrupter that is simple in construction, reliable in operation and relatively inexpensive to manufacture.

Certain features that are herein disclosed are disclosed and claimed in the patent to Gerald J. Frecse, Patent No. 3,211,861, issued Oct. 12, 1965.

The novel features that are considered characteristic of this invention are set forth in particular in the appended claims. The invention itself, both as to construction and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description, when read in conjunction with the accompanying drawings.

In the drawings:

FIGURE 1 is a top plan view of a circuit breaker constructed in accordance with this invention;

FIG. 2 is a sectional view taken substantially along the line IIII of FIG. 1 looking in the direction of the arrows and showing the operating and tripping mechanisms of the circuit breaker;

FIG. 3 is a sectional view taken along the line III-III 'ofFIG. 1 looking in the direction of the arrows and showing the contact structure of one pole of the breaker;

FIG. 4 is a sectional view taken along the line IVIV of FIG. llooking in the direction of the arrows and showing the other pole of the breaker; and

FIG. 5 is a perspective view on a smaller scale of a heater member seen in FIG. 2.

' As shown in the drawings, a circuit breaker 3 comprises a housing 5 (FIG. 1) which is divided into four parts 7, 9, 11 and 13 to facilitate assembly of the breaker. The housingparts are all of molded insulating material.

The two central housing parts 9 and 11 are provided with internal surfaces and recesses for receiving and supportinga circuit-breaker mechanism 14 (FIG. 2) comprising an operating mechanism 15, a trip device 17 and a lighting device 19. The two central housing parts 9 'and 11 are also provided with recesses and surfaces on the outer sides thereof for cooperating with similar recesses and surfaces on the inner sides of the outer housing parts 7 and 13 (FIG. 1) for receiving and supporting theterminals, conductors and contact structures seen in FIGS. 3 and 4. The housing parts 7, 9, 11 and 13 are held together by means of three rivets 21.

In order to mount the circuit breaker in an outlet box, there is provided a pair of brackets 23, one disposed at each end of the breaker housing. Each-of the brackets 23 is provided with a pair of downwardly extending ears 25 (FIG. 2) having openings therein for receiving one of the rivets 21. The brackets 23 have openings 27 therein for receiving means for mounting the breaker on a panel or in an enclosure.

As seen in FIG. 3, the various recesses and surfaces of the housing parts 7 and 9 support a pole unit comprising a conductor 29 having a solderless terminal connector 31 attached to one end thereof and a stationary contact 33 secured to the other end; a conductor 35 having a stationary contact 37 secured to one end thereof and a contact surface 39 at the other end, and a conductor 41 having a contact surface 43 at one end thereof and a solderless terminal connector 45 suitably supported at the other end.

In operation, the stationary contacts 33 and 37 are bridged by an improved movable contact member 47 comprising a generally flat conducting plate 48having two contact surfaces 49 at one end thereof. The plate 48 may be of a suitable conducting material such as copper and the contact surfaces 49 may be of a better conducting material such as silver. The plate 48 has a slot 51 therein for receiving a pin 53 that drives the contact member 47 to slide it endwise or rectilinearly into and out of engagement with the contacts 33, 37 in a manner to be hereinafter specifically described. As seen in FIG. 3, the housing part 9 has two surfaces 55 thereon that provide a track for guiding the member 47 in its path. Upper and lower end surfaces 57 of the contact member 47 are curved as seen in FIG. 3 so that if the contacts 49 or the contacts 33, 37 are slightly out of alignment the contact member 47 can rock in the plane of its fiat surfaces in order to provide adequate contact engagement.

When the movable contact member 47 is in the closed position, the circuit through the pole unit seen in FIG. 3 extends from the terminal 45 through the conductor 41, the contact 43, a plug-in type heater member indicated generally at 61 (FIGS. 2 and 5), the contact 39 (FIG. 3), the conductor 35, the contact 37, the bridging movable contact member 47, the contact 33, the conductor 29, to the terminal member 31. The circuit is opened by movement of the contact member 47 to the open-circuit position seen in FIG. 3.

The various recesses and surfaces of the housing parts 11 and 13 (FIG. 1), support a pole unit (FIG. 4) comprising a conductor 63 having a solderless terminal connector 65 attached to one end thereof and a stationary contact 67 secured to the other end, and a conductor 69 having a solderless terminal connector 71 attached to one end thereof and a stationary contact 73 secured to the other end. Surfaces 75 on the housing part 11 form a track for guiding a contact member 47' that is identical with the contact member 47 seen in FIG. 3 for which reason like reference characters are applied to the contact member seen in FIG. 4, except that the reference characters are primed in FIG. 4. A pin 53' is disposed in the slot 51' of the contact member 47' to move the contact member into and out of bridging contact engagement with the stationary contacts 67, 73 in the same manner as the contact member 47 is moved.

' Although, as shown in FIGS. 3 and 4, the contact members 47 and 47' at first glance appear to move in different directions, it will be understood from noticing the section lines and the direction of the arrows in '1, that actually these movable contact members 47 and '47- move in the same direction upon movement of the pins 53 and 53'. g

When the circuit breaker is closed, the circuit through the pole "unit seen in FIG. 4 extends from the terminal 65 to the conductor 63, contact 67, movable contact member 47, contact 73, conductor 69, to the solderless terminal connector 71.

The contact members 47 and 47' to the open and closed positions by ating mechanism are manually operated operation of the oper- 15 (FIG. 2) which comprises an improved handle-key operating structure 77, an insulating contact operating arm 79, a releasable member 81 and an overcenter spring 83.

The improved handle-key operating structure 77 is of molded insulating material and comprises a lever part 85 pivotally supported by means of two pins 87 (only one being shown in FIG. 2) that are molded integral with the part 85. The pins 87 are pivotally supported in suitable openings in the molded housing parts 9 and 11. The lever part 85 of the operating structure 77 has an opening therein that is shaped to receive and mate with a handle part 89 having two extended parts 91 that fit snuglyinto the opening. Thus, when it is desired to operate the operating structure 77, the handle 89 is placed in position providing leverage for operating the lever part 85, and after operation, the operator can remove the handle part 89 to make it difficult for an unauthorized person to manually operate the circuit breaker.

The operating lever 85 is generally U-shaped, only one leg 93 thereof being seen in FIG. 2. Each of the legs 93 is itself generally U-shaped as seen in FIG. 2 and each generally U-shaped leg 93 receives in the opening between its legs a pin 95 that is molded integral with the contact operating arm 79. The contact operating arm 79 is generally U-shaped only one leg being seen in FIG. 2, and each leg thereof carries one of the pins 95 that is disposed in the opening between the legs of one of the U-shaped legs 93. An overcenter spring 83 is connected at one end to the bight part of the U-shaped contact operating arm 79 and at the other end in a suitable depression in the releasable member 81. The releasable member 81 is pivotally supported at 97 by means of a pivot pin that is rotatably seated in suitable openings in the housing parts 9 and 11. The other or free end 99 of the releasable member 81 is latched in an opening in a bimetal structure 101. Each of the pins 53 and 53' (FIGS. 3 and 4, respectively) is molded integral with one of the legs of the U-shaped contact operating arm 79 (FIG. 2) and is disposed in the associated slot 51 or 51' (FIGS. 3 and 4) in the associated movable contact member 47 or 47'. v The circuit breaker is shown in the open circuit position in FIGS. l4. When it is desired to close the circuit breaker,-the handle portion 89 is inserted into the operating lever 85, and rotated counterclockwise (FIG. 2) from the off to the on position about the pivot 87. This movement because of the engagement of the U-shaped legs 93 of the operating lever 85 with the pins 95 of the contact operating member 79, and also because of the engagement of the pins 53 and 53' in the slots 51 and 51 of the contact members 47 and 47' moves the contact operating arm 79 down the members 47 and 47 being prevented from moving back by engagement thereof with surfaces 103 and 103 that are formed on the housing members 9 and 11 charging the overcenter spring 83. During this motion, the line of action of the overcenter spring 83 is moved to the left of a straight line drawn between the centers of the pins 53, 95 and 87, whereupon the overcenter spring 83 discharges snapping the lower part of the movable contact arm 79 to the left (FIG. 2) and moving the pins 53 and 53 to the left to move the movable contacts 47 and 47 (FIGS. 3 and 4) into engagement with their respective stationary contacts 33, 37 and 67, 73.

Thereafter, the handle portion 89 can be removed until it is desired to then open the circuit breaker. In order to manually open the circuit breaker, the handle portion 89 is placed in position in the operating lever 85 and rotated from the on to the off position (FIG. 2) during which movement the line of action of the overcenter spring 83 is moved to the right of a straight line through the centers of the pins 53, 95 and 87, whereupon the spring 83 discharges snapping the movable contact arm 79 back to the position seen in FIG. 2, which movement, by virtue of the engagement of the pins 53 and 53 in the 4 slots 51 and 51', respectively, of the contact members 47 and 47' (FIGS. 3 and 4), moves the movable contact members 47 and 47' back to the open-circuit position seen in FIGS. 3 and 4 with a snap-action.

The circuit breaker is automatically tripped open upon the occurrence of an overload current condition above a predetermined amount by means of the trip device 17 (FIG. 2) comprising the plug-in heater member 61 (FIGS. 2 and 5), the bimetal structure 101 (FIG. 2), a calibrating and adjusting screw 105 and an adjusting member 107. The bimetal structure 101 is welded or otherwise secured to an L-shaped bracket 109 that is suitably secured to the housing parts 9 and 11. -As was hereinbefore explained, the bimetal structure 101 has an opening in the lower or free end thereof forming a lower edge upon which one end 99 of the releasable member 81 is latched.

The bimetal structure 101 comprises a first part 111 and a second part 112. The second part 112 is lanced out of the part 111 and it extends generally normal to the part 111*(FIG. 2). The calibrating screw 105 is supported in a tapped opening in one leg of the bracket 109 and it engages the lanced-out part 112 of the bimetal structure 101. The upper end of the screw 105 has a not-ch 113 therein for receiving a screwdriver or other tool.

The plug-in heater member 61 (FIGS. 2 and 5) comprises a supporting frame 117 of molded insulating material having secured thereto two conducting plates 119 and 121. A resistance wire 123 is secured at one end 125 to the conducting plate 119 and at the other end 127 to the conducting plate 121. An insulating sheet 129 is provided between the resistance wire 123 and the conducting plates 119, 121, except where the connections 125, 127 are made. When the heater member 61 is in operating position, a lower contact portion 131 on the conducting plate 119 engages the contact 39 (FIG. 3) of the conductor 35, and an upper contact portion 133 (FIG. 5) on the conducting plate 121, engages the upper contact portion 43 (FIG. 3) of the conductor 41. Thus, when the plug-in heater is in position, the circuit through the pole seen in FIG. 3, extends from the contact 39 through the contact 131 (FIG. 5), the conducting plate 119, the resistance wire 123, the conducting plate 121, the contact 133, to the contact 43 (FIG. 3

When an overload current above a predetermined amount occurs in the circuit controlled by the closed circuit breaker, the resistance wire 123 is heated to inductively heat the bimetal structure 101 (FIG. 2). The high expansion side of the bimetal part 111 is on the left as seen in FIG. 2, so that when the bimetal is heated sufficiently, the bimetal part '111 bends and the lower end thereof moves to the right to release or unlatch the releasable member 81. When the releasable member 81 is released, the member 81, under the bias of the overcenter spring 83, is pivoted clockwise about its pivot 97 moving the lever 85, the contact operating arm 79, and the overcenter spring 83 to positions wherein the line of action of the spring 83 is to the right of a straight line through the centers of the pins 53, 95 and 87, whereupon the spring 83 operates to move the contact operating arm 79 to thereby move the contacts 47, 47 to the open position. During this movement, the lever 85 (and the handle 89 if it is secured thereto) is moved to a center position intermediate the on and 011 positions to provide a visual indication that the circuit breaker has tripped open.

After a tripping operation, the breaker is relatched by manual movement of the handle 89 and lever 85 to the extreme off position during which movement a part 137 of the lever 85 engages a pin 139 on the releasable member 81 to move the releasable member 81 counterclockwise about the pivot 97 to relatch the end 99 on the bimetal 101. Thereafter, the circuit breaker is manually operated, in the same manner hereinbefore described, by movement of the handle 89.

The circuit breaker is calibrated when it is assembled at the factory. This calibrating operation comprises running a predetermined overload current through the breaker and rotating the screw 105 to vary the amount of latching engagement between the end 99 of the releasable member 81 and the latching surface of the bimetal 101 until the circuit breaker trips with the desired time delay being considered in the calibrating operation. Thereafter, the part 107 is secured to the member 105 and cemented to this member so that it becomes a permanent part of the trip device.

The member 107is part of improved means for adjusting the trip device to a limited extent in the field. Referring to FIG. 1, it will be seen that the member 107 is disposed partially in a cup-shaped opening 141 in the housing parts 9 and 11. A slot 143 is provided in the adjusting member 107 to receive a screwdriver. When it is desired to adjust the trip device, the member 107 is rotated either clockwise or counterclockwise (FIG. 1) to move the bimetal 101 to thereby vary the amount of latch engagement between the releasable member 81 and the bimetal 101.

When the bimetal structure 101 is in the normal position shown in FIG. 2, the part 111 thereof is flexed slightly to the right by means of the screw 105. Thus, if it is desired to adjust the trip device 17 so that the breaker will trip upon the occurrence of a greater minimum overload, the member 107 is rotated counterclockwise (FIG. 1) to move the screw 105 up (FIG. 2) to permit the bimetal structure 101 to unfiex to the left. This move ment of the bimetal structure 101 increases the amount of latch engagement between the releasable member 81 and the bimetal 101 so that the breaker will trip upon the occurrence of a greater minimum overload. If the adjusting member 107 is rotated clockwise (FIG. 1) the screw 105 is moved down (FIG. 2) to move the bimetal structure 101 to the right. This movement decreases the amount of latch engagement between the releasable member 81 and the bimetal structure 101 so that the breaker will trip upon the occurrence of a lesser minimum overload.

The adjusting member 107 is limited to rotation of less than 90 in either direction, from the position in which it is seen in FIG. 1, by means of stop surfaces 145 thereon that engage with stop surfaces 147 on the housing parts 9 and 11. Thus, the trip mechanism cannot be overadjusted in the field in a manner that would damage the bimetal or prevent interruption of the circuit upon the occurrence of a damaging overload.

The indicating lamp 19 is supported in a suitable opening 151 in the housing parts 9 and 11 and two leads 153 and 155 from the lamp 19 can be connected across-theline in the terminals 45 (FIG. 3) and 65 (FIG. 4) in order to provide a visual indication of whether the circuit controlled by the breaker 3 is closed or opened. A plastic cap 157 having two ears 159 thereon is provided over the lamp 19 for protection of the lamp. The cars 159 are placed down into depressions 161 (FIG. 1) in the housing parts 9 and 11 when the cap 157 is being mounted and the cap is then rotated slightly whereupon the ears 159 move within a slot in the housing to a position where they are out of alignment with the depressions 161. The cap 157 is thus locked in place.

The improved movable contact member comprises a generally fiat plate of solid conducting material that is simple and efficient to manufacture and will stand up under rigorous continuous operation of the circuit breaker. The flat plate slides rectilinearly within a track and it has curved surfaces that engage the opposite sides of the track to permit the contact member to .rock in the plane of its largest flat surfaces, thereby providing for good contact engagement even when the contacts are slightly out of alignment.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details thereof may be made without departing from some of the essential features of the invention.

We claim as our invention:

1. A circuit breaker comprising stationary. contact means, a movable contact member comprising a generally flat plate having contact means at one end thereof, two generally parallel track surfaces, said track surfaces engaging oppositely disposed end surfaces of said plate to guide said plate, means operable to move said plate between said track surfaces into and out of engagement with said stationary contact means, and said oppositely disposed end surfaces of said plate being curved surfaces to permit said plate to rock in the planes of its largest flat surfaces.

2. A circuit interrupter comprising stationary contact means, said stationary contact means comprising a pair of spaced butt-type contacts, a bridging movable contact member comprising a generally flat member of conducting material having a pair of butt-type contact surfaces at one end thereof, track means, said track means and end surface means of said movable contact member comprising surface-engaging means guiding said movable contact member for endwise movement along planes parallel to the fiat faces of said movable contact member, an insulating operating member, overcenter spring means manually operable to operate said insulating operating member between operating positions, and lost-motion connecting means connecting said insulating operating member with said movable contact member whereby operation of said insulating operating member operates to move said movable contact member to thereby move said butt-type contact surfaces into and out of butting engagement with said pair of spaced butt-type contacts, and said surfaceengaging means comprising means to permit said movable contact member to rock in the planes of the flat faces of said movable contact member for contact alignment.

3. A circuit interrupter comprising stationary contact means, a conducting plate member having contact means at one end thereof, opositely disposed end surfaces of said plate member comprising curved surfaces, two generally parallel track surfaces engaging said oppositely disposed end surfaces of said plate member to guide said plate member, an insulating operating member, overcenter spring means operable to operate said insulating operating member between operating positions, lost-motion connecting means connecting said insulatig operating member with said plate member to provide for operative movement of said plate member on said track surfaces into and out of engagement with said stationary contact means upon operation of said insulating operating member, and said curved surfaces of said plate member permitting said plate member to rock in the planes of the largest fiat surfaces of said plate member for contact alignment.

4. A circuit interrupter comprising an insulating housing structure, said insulating housing structure having two pairs of oppositely disposed track surfaces thereon, a bridging movable contact plate for each of said pairs of track surfaces, each of said separate contact plates having oppositely disposed end surfaces engaging the associated track surfaces to guide the plate for generally rectilinear endwise movement on the associated track surfaces, said oppositely disposed end surfaces of each of said separate contact plates being curved to permit each of said separate contact plates to rock in the planes of the largest flat surfaces thereof to thereby provide for contact alignment, a separate pair of spaced butt-type stationary contacts supported opposite one end of each of said contact plates, an insulating operating member supported between said contact plates, lost-motion slot-and-pin connecting means connecting said insulating operating member with said contact plates, an overcenter spring operating means operable to operate said insulating operating member between operating positions and comprising a handle member extending from said housing and movable between operating positions, and upon operation of said handle member said insulating operating member moving to simultaneously move said contact plates endwise into and out of bridging butt-type engagement with said butt-type spaced stationary contacts.

5. A circuit breaker comprising stationary contact means, said stationary contact means comprising a pair of spaced stationary butt-type contact members, a bridging movable contact member comprising a generally flat conducting plate having a pair of butt-type contact surfaces at one end thereof, two generally parallel insulating track surfaces, said generally parallel insulating track surfaces engaging oppositely disposed end surfaces of said plate to guide said plate for generally rectilinear endwise movement, means operable to move said plate between said track surfaces to move said butt-type contact surfaces into and out of bridging butt-type engagement with said butt-type stationary contacts, and said oppositely disposed end surfaces of said plate being curved surfaces to permit said plate to rock in the planes of the largest flat surfaces thereof for contact alignment.

6. A circuit breaker comprising stationary contact means, said stationary contact means comprising a pair of spaced stationary butt-type contact members, a bridging movable contact member comprising a generally flat conducting plate having a pair of butt-type contact surfaces at one end thereof, track means, said track means and end-surface means of said movable contact member com prising surface-engaging means for guiding said movable contact member for generally rectilinear endwise movement, means operable to move said movable contact member on said track means to move said butt-type contact surfaces into and out of bridging butt-type engagement with said butt-type stationary contact members, and said surface-engaging means comprising means to permit said movable contact member to rock in the planes of the largest flat surfaces of said movablecontact member for contact alignment.

References Cited by the Examiner UNITED STATES PATENTS 1,853,752 4/1932 Wadsworth 20076 2,037,544 4/1936 Seaman 20076 2,103,070 12/1937 Frank 20076 2,109,378 2/1938 Bentley ZOO-76 2,285,887 6/1942 Benander 200159 ROBERT K. SCHAEFER, Primary Examiner.

D. SMITH, JR., Assistant Examiner. 

1. A CIRCUIT BREAKER COMPRISING STATIONARY CONTACT MEANS, A MOVABLE CONTACT MEMBER COMPRISING A GENERALLY FLAT PLATE HAVING CONTACT MEANS AT ONE END THEREOF, TWO GENERALLY PARALLEL TRACK SURFACES, SAID TRACK SURFACES ENGAGING OPPOSITELY DISPOSED END SURFACES OF SAID PLATE TO GUIDE SAID PLATE, MEANS OPERABLE TO MOVE SAID PLATE BETWEEN SAID TRACK SURFACES INTO AND OUT OF ENGAGEMENT WITH SAID STATIONARY CONTACT MEANS, AND SAID OPPOSITELY DISPOSED END SURFACES OF SAID PLATE BEING CURVED SURFACES TO PERMIT SAID PLATE TO ROCK IN THE PLANES OF ITS LARGEST FLAT SURFACES. 